java - 无法在内存中的 sqlite 数据库上创建表，没有任何错误消息

Question

我正在尝试在内存中的 sqlite 数据库上创建一个表。我有一个名为 createTable 的方法来创建一个表，该表使用 getConnection 方法初始化与数据库的连接。

创建表:

private void createTable() {
    try {
        final Connection connection = getConnection();
        final Statement statement = connection.createStatement();
        statement.execute(
            "CREATE TABLE videos (id INTEGER PRIMARY KEY, title VARCHAR(255), description TEXT, path TEXT, category VARCHAR(255), published INTEGER DEFAULT 0, created TIMESTAMP DEFAULT CURRENT_TIMESTAMP);");
        statement.close();
        connection.close();
    } catch (final SQLException e) {
        LOGGER.warn("Failed to create table.", e);
    }
}

获取连接

private static Connection getConnection() {
    try {
        Class.forName("org.sqlite.JDBC");
        return DriverManager.getConnection("jdbc:sqlite:");
    } catch (final Exception e) {
        LOGGER.warn("Failed to get connection.", e);
        throw new RuntimeException(e);
    }
}

为了测试数据库，我写了一个简单的insert方法:

public void insert() {
    try {
        final Connection connection = getConnection();
        final Statement statement = connection.createStatement();
        statement.executeUpdate(
            "INSERT INTO videos (title, path, category) VALUES ('test title', 'test path', 'test category');");
        statement.close();
        connection.close();
    } catch (final SQLException e) {
        LOGGER.warn("Failed to insert.", e);
    }
}

当我这样做

this.createTable();
this.insert();

我收到以下错误:

2017-09-17 22:38:02 WARN  Database:128 - Failed to insert.
org.sqlite.SQLiteException: [SQLITE_ERROR] SQL error or missing database (no such table: videos)
    at org.sqlite.core.DB.newSQLException(DB.java:909)
    at org.sqlite.core.DB.newSQLException(DB.java:921)
    at org.sqlite.core.DB.throwex(DB.java:886)
    at org.sqlite.core.NativeDB._exec_utf8(Native Method)
    at org.sqlite.core.NativeDB._exec(NativeDB.java:87)
    at org.sqlite.jdbc3.JDBC3Statement.executeUpdate(JDBC3Statement.java:116)...

对于连接，我使用的是 org.xerial:sqlite-jdbc 的 v3.20.0。

为什么没有创建表的任何想法？我没有看到任何异常或任何东西。 SQLFiddle for the example above好像没问题。

Answer 1

如果我阅读 the documentation正确地，默认情况下数据库仅存在于其数据库连接中:

Instead, a new database is created purely in memory. The database ceases to exist as soon as the database connection is closed. Every :memory: database is distinct from every other. So, opening two database connections each with the filename ":memory:" will create two independent in-memory databases.

最简单的解决方法是不打开第二个连接，而是继续使用您用于为其他数据库查询创建表的连接。

如果要打开多个连接，可以在数据库url上设置?cache=shared参数。